The Animal Imaging Core provides a wide array of non-invasive, high resolution quantitative imaging-based capabilities for metabolic and genetic characterization of tumors and their microenvironment. Among the critical scientific applications of small-animal imaging by MSKCC investigators are: phenotypic screening of tumor incidence, progression and therapy-induced regression in xenograft models and transgenic/knock-out models; assessment of trafficking of cancer cells, stem cells, and immune effector cells in vivo; evaluation of trans-gene expression, development, testing, and validation of targeted therapies (i.e. pharmacodynamics); and detection and localization of tumor hypoxia and re-oxygenation. These capabilities are broadly applicable to the fundamental mission of the Center in areas such as molecular imaging, assessment of therapeutic response, and drug development. The services provided by the Animal Imaging Core has supported the research of 65 investigators in the past year. During the past grant period the work of the Core has contributed to 370 publications of researchers from 9 research programs. As part of a major expansion and modernization of MSKCC's infrastructure, the Imaging Core has been consolidated and re-located to the Zuckerman Research Center's vivarium. This area provides enhanced biosecurity and functionality and houses the R4 and Focus 120 microPET, ivis 100 opfical imaging system, microCATII, microCT, NanoSPECT/CT Plus, SPECT-CT, Maestro, FMT 2500 near-Infrared fluorescence tomography system, and Vevo 2100 ultrasound system. The existing Ivis 100 optical imaging system remains at the Rockefeller Research Laboratory, supporting investigators In that building. A new high precision microirradiator, X-RAD, for rodent tumors and other structures was installed in 2012. The Core's 4.7T and 7.0T Brucker USR systems have also been moved to the Vivarium. The Core has provided critical support for the development and characterization of mouse models for human cancer. For example, models for glioma driven by PDGF-B signaling and anaplastic thyroid tumors driven by inducible mutant BRAF have been extensively characterized and examined for therapeutic responses using the imaging resources of the Core.